Evaluation of the Survival of Salmonella spp. and Escherichia coli O157:H7 in Unpasteurized Apple Juice from Juice Bars

Introduction: Juice bars continue to gain popularity. Because unpasteurized juice served in juice bars is not thermally processed, these products may contain pathogens. Although the safety of unpasteurized juice has been studied, research has not focused on the microbiological safety of juice produced in juice bar conditions.

Purpose: The objective of this study was to evaluate the survival of Salmonella spp. and Escherichia coli O157:H7 in unpasteurized juice at two different juice bars.

 Methods: Unpasteurized apple juice (Brands A and B) was purchased and inoculated with Salmonella spp. and E. coli O157:H7 (10⁸ CFU/ml) and stored at 4°C and 23°C. Survival was evaluated over 14 days. Samples were plated on XLD and SMAC and incubated (37°C, 24 hr). Brands C and D served as pasteurized controls.

Results: As it relates to Salmonella spp., the Brands significantly affected (P<0.01) growth. Brand B displayed the highest pH (4.21) while having the lowest log reduction (3.13 log CFU/ml). A reduction of 4.06 log CFU/ml was observed in Brand D, which is significantly different (P<0.01) from Brands A (3.32 CFU/ml) and B (3.14 log CFU/ml). The microbial load of Brand C was 3.69 log CFU/ml. Brands held at 4°C were significantly different in population compared to brands held at 23°C. As it relates to E. coli O157:H7, the highest inhibition of E. coli O157:H7 (P<0.05) was observed in Brands C and D compared to Brands A and B. The results showed a significant (P<0.05) reduction of E. coli O157:H7 populations by 3.62 log in Brand D, 3.31 log CFU/ml in Brand C, 0.25 log CFU/ml in Brand B, and 1.52 log CFU/ml in Brand A when stored at 4°C. Greater inhibition was observed at 4°C than at 23°C.

Significance: Unpasteurized apple juice in juice bars has more potential for survival of E. coli O157:H7 and Salmonella spp.